School of Pharmacy
Numerous behavioral studies indicate that dopamine transporter (DAT) inhibitors and metabotropic glutamate receptor 5 (mGlu5) negative allosteric modulators (NAMs) possess promising anti-addiction therapeutic properties. However, the lack of human DAT (hDAT) and mGlu5 X-ray crystal structures makes it difficult to understand how these promising anti-addiction compounds interact with their major drug targets at the molecular level. This knowledge gap represents an important problem towards rationally designing new therapeutics for numerous addiction disorders. The objective of this research was to develop irreversible chemical probes based on select DAT inhibitors and mGlu5 NAMs in order to map the corresponding binding sites and poses of these compounds within their major drug targets. The central hypothesis was that these compounds could be derivatized, without significant loss in pharmacological activity, with a functional group capable of forming a covalent bond to their target protein and, if necessary, a tag functional group. These probes would then allow proteomic experiments to be coupled with computational modeling in order to directly map the ligand-binding sites of these promising anti-addiction compounds within their target proteins. The central hypothesis was tested by pursuing two specific aims: 1) identification of non-tropane DAT inhibitor photoprobes suitable for DAT structure-function studies, and 2) identification of irreversible mGlu5 NAM ligands as chemical probes suitable for mGlu5 structure-function studies. Under the first aim, methylphenidate (MP) and GBR-12909 as non-tropane DAT inhibitors were structurally modified to contain a photoreactive group (e.g., aryl azide, benzophenone) and a tag (e.g., 125I, terminal alkyne, aliphatic azide). These compounds were then subjected to DAT pharmacological evaluation in order to identify suitable candidates for DAT structure-function studies. Under the second aim, thiazole- and pyridine-based mGlu5 NAMs were structurally modified to contain either a photoreactive group (e.g., aryl azide, benzophenone) or an affinity labeling group (e.g., methanethiosulfonate, maleimide) and a tag (e.g., 125I, terminal alkyne, aliphatic azide). These compounds were then subjected to mGlu5 pharmacological evaluation in order to identify suitable chemical probe candidates for mGlu5 structure-function studies. At present, several irreversible chemical probes from these specific aims have advanced to the proteomics stage of the experimental research strategy.
Velagaleti, R. (2014). Dopamine Transporter (DAT) and Metabotropic Glutamate Receptor 5 (MGLU5) Irreversible Probes for Identifying Anti-Psychostimulant Therapeutics (Doctoral dissertation, Duquesne University). Retrieved from https://dsc.duq.edu/etd/1306